1. Technical Field
The present disclosure relates to a power transmission device that transmits AC electric power noncontact by electromagnetic inductance between a transmission coil and a reception coil, a vehicle equipped with the power transmission device, and a wireless power transmission system.
2. Description of the Related Art
Various mobile devices such as cellular phones have come into widespread use. The electric power consumption of mobile devices continues to rise, due to improved functions and performance, and a wider variety of contents. If the electric power consumption of a mobile device operated with a battery having a capacity that is fixed beforehand increases, the operating time of the mobile device becomes shorter. Wireless power transmission systems are gathering attention as a technology to make up for restrictions of battery capacity. A wireless power transmission system operates by electromagnetic induction between a power transmission coil in a power transmission device and a power receiving coil in a power receiving device causing noncontact transmission of AC power from the power transmission device to the power receiving device. Particularly, a wireless power transmission system using a resonance power transmission coil and a resonance power receiving coil can maintain high transmission efficiency even if the positions of the power transmission coil and the power receiving coil are deviated. Accordingly, resonance wireless power transmission systems are applied in various fields.
As of recent, systems where a power transmission device to perform noncontact charging of mobile devices (power receiving devices) such as cellular phones and so forth is installed in a vehicle are starting to come into use. These systems enable noncontact charging of mobile devices in a car. The power transmission device desirably is constituted as thin as possible, to take up as little space as possible.
An example of such related art is disclosed in Japanese Unexamined Patent Application Publication No. 2008-205215. However, this related art has a problem in that forming the power transmission device thinner increases the loss of the power transmission coil, and transmission efficiency decreases. Accordingly, there has been demand for a power transmission device that transmits AC power with high efficiency.